<?php
class UUID{

	/**
     * uuid
	 * @param string prefix 前缀
     * @return string uuid
     */
    public static function uuid($prefix = "")
    {
        $chars = md5(uniqid(mt_rand(), true));
        $uuid = substr($chars, 0, 8) . '-'
            . substr($chars, 8, 4) . '-'
            . substr($chars, 12, 4) . '-'
            . substr($chars, 16, 4) . '-'
            . substr($chars, 20, 12);
        return $prefix . $uuid;
    }

}